Improved diesel lubricants



United States Patent Ofiice 3,007,869 Patented Nov. 7, 1961 3,007,869 IMPRGVED DIESEL LUBRICANTS Roland C. Nunn, Carteret, N.J., assignor t Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed June 29, 1959, Ser. No. 823,318 Claims. (Cl. 252-33.4)

This invention relates to improved lubricants and their preparation. More particularly, this invention relates to lubricating compositions comprising a major proportion of a hydrofined, and phenol extracted coastal distillate, boiling at mm. Hg pressure, between 340 and 700 F. and derived from a naphthenic crude, as a lubricating oil base; and minor amounts of an alkaline earth phenol sulfide, an alkaline earth sulfonate and phenyl-anaphthylamine.

The lubricants of this invention are extremely useful as low cost, high performance, crankcase lubricants for railway diesel locomotives. These lubricants are particularly adapted for engines equipped with silver or copper-lead bearings. In addition, the lubricants of this invention are more simply and economically prepared since they contain but a single base stock, while the diesel crankcase lubricants of the prior art are normally prepared from a rather complex blend of a conventionally refined (i.e., acid treated and/or phenol extracted, clay contacted) coastal distillate, bright stock, and filtered neutral.

The basis of the present invention is the discovery that a new and unexpectedly improved lubricating oil composition may be formed from a hydrofined and phenol-extracted coastal distillate by the addition of specific synergistic amounts of an alkaline earth sulfonate and of an alkaline earth metal salt of a phenol sulfide and a small proportion of phenyl-wnapthylamine. In the prior art, numerous lubricating oil compositions have been disclosed which contain metal sulfonates and/or alkaline earth metal phenol sulfides as detergent inhibitors. The use of phenyl-wnaphthylamine has also been disclosed in the prior art as an oxidation inhibitor. The prior art, however, does not disclose the use of the combination of these additives in a hydrofined and phenolextracted base stock or the fact that the combination of these additives in this particular type of base stock will result in new and unexpectedly improved properties. The improved properties of the lubricants of this invention are obtained only by the use of these particular additives in the hydrofined and phenol-extracted base. Also, the weight percent and relative ratios of the additives are critical as regards the improved properties of the finished lubricant.

The lubricants of this invention comprise a major proportion of a hydrofined and phenol-extracted coastal distillate, boiling between 340 and 700 F. at 10 mm. Hg pressure, and having a viscosity index in the range of 50 to 80 and a viscosity at 100 F. in the range of 800 to 1200 SSU; 1 to 5 volume percent of an alkaline earth metal salt of an alkyl phenol sulfide; 1.5 to 8 volume percent of an alkaline earth metal sulfonate; and 0.2 to 1.0 weight percent, based on the total weight of the above formulation, of phenyl-ot-naphthylamine. Preferably the lubricants will comprise a major proportion of the above base oil, about 1.5 to 4 volume percent of mixed alkaline earth metal salts of C to C alkyl phenol sulfide, 2 to 5 volume percent of an alkaline earth metal sulfonate, and about 0.4 wt. percent, based on the total Weight of the above formulation, of phenylu-naphthylamine.

The lubricating oil base is prepared by hydrofining a coastal distillate, boiling at 10 mm. Hg pressure between 340 to 700 F., in a fixed bed catalytic process at temperatures in the range of 500 to 700 of 400 to 800 p.s.i. Hydrofining of mineral lubricating oils is well known in the art and is extremely effective in improving color and reducing the neutralization number, sulfur and Conradson carbon residue. Hydrofining is normally conducted until the sulfur content of the mineral oil is below about 0.18 wt. percent. Following hydrofining, the lubricating oil base is phenol extracted by methods well known in the art. Phenol extraction is used to remove aromatic type components from the feed stock and thereby raise the viscosity index and improve the oxidation stability and color of the lubricating oil base. Phenol extraction is conducted until a. lubricating oil base stock having a viscosity index in the range of 50 to and preferably in the range of 60 to 75 is obtained. In the processing of the coastal distillate base stocks of this invention, either hydrofining or phenol extraction may be employed as the initial processing step. The term hydrofined and phenol-extracted therefore is intended to include both hydrofined-phenol extracted and phenol extracted-hydrofined coastal distillates.

The alkaline earth metal salts of an alkyl phenol sulfide are well known in the prior art and are described in numerous US. patents. See, for example, US. Patents 2,362,289; 2,461,335, and 2,480,664. Of these metal salts the mixed alkaline earth metal salts are preferred. These mixed metal salts are prepared by neutralizing a phenol sulfide with a mixture of basic compounds of the alkaline earth metals, for example, the hydroxides, or they may be prepared by first partially neutralizing the phenol sulfide with one of the metals and then completing the neutralization by treatment with a suitable basic compound of the other metal. The alkyl phenol sulfide will preferably have an alkyl side chain of 5' to 25 carbon atoms attached to each benzene nucleus. The mixed metal portion of the salt will normally consist of 15 to wt. percent of calcium and 85 to 15 percent of a metal selected from the group consisting of other alkaline earth metals, preferably barium.

The alkaline earth metal sulfonates may be alkaline earth metal salts of petroleum sulfonates or high alkalinity calcium or barium synthetic sulfonates well known in the art. Calcium sulfonates are preferred because of their anti-wear properties on silver bearings. Preferably the sulfonic acid portion of the metal salt will have a molecular weight in the range of about 500 to 1000. The calcium sulfonate will contain 2 to 5 weight percent calcium and the barium sulfonate will contain 10 to 20 weight percent barium.

Phenyl-a-naphthylarnine is well known in the prior art and has been used in various lubricating oil compositions as an anti-oxidant. Phenyl-a-uaphthylamine and its preparation are disclosed in US. Patent 1,988,299.

Minor amounts of conventional viscosity index improvers and/ or pour depressants such as polyisobutylene or polymethacrylates and anti-foam agents such as silicone fluids, may be incorporated in the lubricants of this invention, if desired.

The improved properties of the diesel lubricants of this invention, as well as the surprising discovery that the utility of the additives of this invention will vary with the type of refined mineral oil base stock, are shown in the examples which follow. Thus, these examples are submitted as explaining and further defining the improved lubricants of this invention.

EXAMPLE I A diesel crankcase lubricant of this invention was prepared by adding 2.4 wt. percent (2.25 vol. percent) of a calcium and barium mixed salt of nonyl phenol sulfide, and 4.2 wt. percent (4.0 vol. percent) of calcium sul- F. and pressures fonate (45 wt. percent concentration in mineral oil of 100 SSU viscosity at 100 F.) having a molecular weight of about 925, to 93.4 wt. percent (93.75 vol. percent) of a hydrofined (at 650 F.) and phenol extracted coastal distillate (boiling at 10 mm. Hg pressure between 440 and 680 F.) having a viscosity index of 63 and a viscosity at 100 F. of 1100 SSU. Next 0.4 wt. percent (based on the total weight of the above formulation) of phenyla-naphthylamine was added to the compounded lubricant. The above formulation is hereinafter designated Oil A.

A lower viscosity version of Oil A may be prepared by using the same additives in a hydrofined and phenol extracted coastal distillate (boiling between 360 and 680 F. at 10 mm. Hg pressure) having a viscosity index of 63 and a viscosity at 100 F. of 1020 SSU. This formulation is hereinafter designated Oil A A third formulation, Oil B, of the crankcase lubricants of this invention was prepared by adding 2.4 wt. percent (2.25 vol. percent) of the calcium and barium mixed salt of nonyl phenol sulfide and 3.3 wt. percent (2.75 vol. percent) of high alkalinity barium sulfonate (45 wt. percent concentration in mineral oil of 100 SSU viscosity at 100 F.), to 94.3 wt. percent (95.0 vol. percent) of the hydrofined and phenol extracted coastal distillate of Oil A. Then 0.4 wt. percent (based on the total weight of the above formulation) of phenyl-a-naphthylamine was added to the compounded lubricant.

Table I, shows the physical and analytical data obtained for Oils A, A and B.

Table I PHYSICAL AND ANALYTICAL DATA Lubricants Inspections Oil A Oil A1 Oil B Viscosity, SSU at- 210 F 80. 1 77. 2 80.0 Viscosity index. 63 63 63 Gravity APL 23.8 24. 2 23. 3 Flash F 480 480 485 Nen No. (D-664):

TAN- 0.74 0.74 0.15

TBN 2. 53 2. 53 3. 69 Sulfated ash, weight percent. 0. 72 0.72 1.06 Barium, weight percent. 0. 05 0.05 0. 52 Calcium, weight percent 0. 15 0. 15 0.05

Table II STABILITY OF UNINHIBITED COASTAL DISTILLATE COMPONENT OXIDATION Viscosity increase, SSU Processing of coastal distillate component at 100 F.

(bearing corr. test, 20 hrs, 325 F.)

Acid treated, clay contacted. 769 Phenol-extracted, clay contacted 569 Hydrofined, clay contacted 1, 463 Hydrofined, phenol-extracted 849 Hydrofined 1, 299

In the above table the viscosity increase in terms of SSU 100 F. is measured after heating the coastal distillate to 325 F. for 20 hours in the presence of copperlead bearings and intimate mixing with air.

From the above table it would appear that a phenolextracted, clay contacted coastal distillate would be the best base stock to use with the additives of this invention for formulating a crankcase lubricant as regards oxidation stability. Therefore, the additives of this invention were added to '(1) the phenol-extracted, clay contacted coastal distillate of Table II (having a VI of 63 and a viscosity at 210 F. of SSU), and (2) tothe hydrofined, phenol-extracted coastal distillate of this invention (having a VI. of 63 and a viscosity at 210 F. of 80 SSU). The resultant lubricants were then tested for oxidation and corrosion properties.

Table III, shows the compositions in terms of volume percent and the properties obtained for both types of base stocks.

Table III OXIDATION AND CORROSION PROPERTIES OF CONVENTIONAL 1 VERSUS HYDROFINED 2 LUBRICANTS EMD silver corr. Vol .percent Properties, test bearing Weight viscosity weight loss, mg. Base stock, vol. percent, increase, Lubricant percent 63 V.I. phenyl-a- SSU at 80 SSU at 210 F. Ba-Ca Ca sulfo- Ba sulfonaphthyl- 100 F. (bear- Ba nonyl nonyl nate (30 natc (45 amine ing corr. test phenol phenol weight weight 20 hrs. 340 Silver Copper sulfide sulfide percent percent cone.) a cone.) 3

B 95.0 conventional 2. 25 0. 4 207 1. 8 0.6 B 0 hydrofined. 2. 25 0. 4 98 1. 6 0. 4 C- 95.0 conventiona 3. 33 1.67 0. 4 286 C 95.0 hydrofined- 3. 33 1. 67 0. 4 277 D 95.0 c0nventional 3. 33 1.67 0. 4 343 7. 4 0 5 D 95.0 hydrofined 3. 33 1. (i7 0. 4 284 2.1 0.6 E 95.0 conventional.. 2. 25 2. 75 0. 4 374 3. 6 2.1 E 95.0 hydrofined 2. 25 2. 75 0. 4 247 3. 7 0. 7

1 Conventionalphenol extracted and clay contacted.

The above table shows that lubricants B, C, D, and E which represent the lubricants of this invention have superior oxidation resistance and anticorrosive properties as compared to similar crankcase lubricants B, C, D, and E formed with conventionally refined coastal distillate base stocks. The fact that the hydrofined, phenol-extracted lubricants of this invention have superior oxidation stability is indeed unexpected in view of Table II.

The EMD Silver Corr. Test of Table III is used to determine the corrosiveness of lubricants toward the silver bearings which are used in General Motors, Electro'Motive Division Railway Locomotives. The test is conducted by heating a sample to 325 F. for 72 hours with mild stirring and in the presence of a section of a silver bearing and a copper strip.

The following tests were run to illustrate the fact that the superior oxidation resistance of the lubricants of this invention is not due merely to the addition of phenyla-naphthylamine as an oxidation inhibitor, but that the superior oxidation resistance is due to a synergistic cooperation between the phenol sulfide, sulfonate, and phenyl-a-naphthylamine with the hydrofined and phenolextracted base. Table IV shows the composition and oxidation resistance of three different lubricants prepared with the 63 V1. hydrofined, phenol-extracted coastal distillate base oil of this invention.

1 In mineral oil of 100 SSU viscosity at 100 F.

The above table clearly shows that it is the combination of additives and not the phenyl-a-naphthylamine which retards oxidation of the oil. In Table IV when either 5.4 wt. percent of the phenyl-a-naphthylamine or sulfide-sulfonate additives are used alone in the 63 V.I. base oil extremely poor oxidation stability is encountered.

Table V illustrates the preparation of the lubricants of this invention at varied concentrations of sulfide, sulfonate, and phenyl-a-naphthylamine. This table shows that while the concentration of phenyl-a-naphthylarnine may be varied between 0.2 and 1.0 wt. percent the best results are obtained at about 0.4 wt. percent concentration of phenyl-oa-naphthylamine and at least 2.0 vol. percent sulfonate.

Table V OXIDATION RESISTANCE AT VARIED CONCENTRATIONS OF ADDI'IIVES Vis. increase Vol, Percent SSU at 100 F.

(bear. corr. V01. Phenyl-atest at 340 F.) Lubripercent naphthylcant 63 amine VI base Ba-Ca Ba sul- Weight nonyl fonate (45 percent phenol weight hrs. 24 hrs. sulfide percent cone.)

1 In mineral oil of 100 SSU viscosity at 100 F.

To further demonstrate the improved properties of the lubricants of this invention, Oils A and B as described above were tested as regards piston deposits in the EMD 2567 Engine Test (i.e., in a full-scale Z-cylinder copy of Electro-Motive Divisions 12- and 16-eylinder railway locomotive engine Model No. 567) and in the Chevrolet L-4 engine test. As a comparison, oil D of Table III (prepared with a phenol-extracted clay contacted coastal distillate) was also subjected to the same tests. Tables VI and VII give the results of these tests.

The piston deposit merit rating of Tables VI and VII is a visual rating of deposits based on a scale of 0' to 100, 0 representing very heavy deposits and 100 representing no deposits.

Table VI PERFORMANCE IN EMD-2 567 ENGINE TEST Piston deposit merit rating (300 hrs.) Lubri cant Com- Com- Piston Over- Ring Piston pression pression underall Zone skirt groove ring side btms. sticking Inspection of used lubricants after 300 hrs.

Sapon- Liblll- Vis. inc. at Neut. N0. (D-664) Insolubles incacant 100 F. Percent tion N o.

SSU PerpH TAN 'IBN Iso- Resins cent pentane Table VI shows that lubricants A and B of this invention give superior or at least equal performance to Oil D as regards piston deposits in EMD railway diesel engines, and that Oils A and B are highly superior to Oil D as regards oxidation resistance (less viscosity increase) and sludge inhibition (less insolubles).

Table VII Table VII shows that Oils A and B give at least as good performance as Oil D in regard to piston deposits, while being highly superior to Oil D as regards oxidation resistance, sludge inhibition, and corrosion and wear of the copperdead bearing.

The Chevrolet L-4 Engine Test is well known in the art and utilizes a standard 6-cylinder Chevrolet engine fitted with copper-lead bearings. Here the engine was run continuously for 36 hours after which tirne the piston deposits and weight loss of the Cu-Pb bearings were determined, and inspection of the used lubricant was made. The Chevrolet L-4 Engine Test is important since it gives an indication of the oils corrosiveness towards Cu-Pb bearings of the type which are used in many railway diesel locomotive engines.

In summary, this invention relates to the discovery that a new and unexpectedly improved crankcase lubricant can be prepared from a hydrofined and phenol extracted coastal distillate lubricating oil base by adding specific amounts of an alkaline earth metal salt of an alkyl-phenol sulfide, an alkaline earth sulfonate and henyLa-naPhthyIamine.

What is claimed is:

1. An improved lubricating oil composition consisting essentially of a major proportion of a hydrofined and phenol extracted coastal petroleum distillate boiling in the range of from 340 to 700 F. at 10 mm. Hg pressure and having a viscosity index in the range of from about 50 to 80 and a viscosity at 100 F. in the range of from about 800 to 1200 SSU, from about 0.8 to about 4 weight percent of an alkaline earth metal sulfon-ate selected from the group consisting of calcium and barium sulfonates having molecular weights in the range of from about 500 to 1000, from about 1.8 to about 5 Weight percent of an alkaline earth metal salt of an alkyl phenol sulfide selected from the group consisting of barium salts and mixed calcium-barium salts of nonyl phenol sulfide, and from about 0.2 to about 1.0 Weight percent, based on the total Weight of said composition, of phenyl-ot-naphthylamine.

2. The lubricating oil composition of claim 1 wherein said coastal distillate is hydrofined in a fixed bed catalytic process at temperatures in the range of 500 to 700 F. and pressures of 400 to 800 psi, and then phenol extracted to a viscosity index in the range of to 80.

3. The lubricating oil composition of claim 1 wherein said alkaline earth metal sulfonate is calcium sulfonate.

4. The lubricating oil composition of claim 1 wherein said alkaline earth metal sulfonate is calcium sulfonate.

5. The lubricating oil composition of claim 1 wherein said phenyl-u-naphthylamine is present in the concentration range of from about 0.2 to about 0.4 weight percent based on the total weight of said composition.

References Cited in the file of this patent UNITED STATES PATENTS 2,467,176 Zimrner et a1 Apr. 12, 1949 2,606,872 Gaser et al Aug. 12, 1952 2,629,693 Barton et a1 Feb. 24, 1953 FOREIGN PATENTS 729,367 Great Britain May 4, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF C0 EQTION Patent N00 3,007,869 November 7 1961 Roland C Nunn It is hereby certified that error appears in the above numbered paten't requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 9, for "calcium read barium Signed and sealed this 14th day of August 1962 (SEAL) ERNEST w SWIDER. DAVID L A D Attesting Officer Commissioner of Patents 

1. AN IMPROVED LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A HYDROFINED AND PHENOL EXTRACTED COASTAL PETROLEUM DISTILLATE BOILING IN THE RANGE OF FROM 340* TO 700*F. AT 10MM. HG PRESSURE AND HAVING A VISCOSITY INDEX IN THE RANGE OF FROM ABOUT 50 TO 80 AND A VISCOSITY AT 100*F. IN THE RANGE OF FROM ABOUT ABOUT 800 TO 1200 SSU, FROM ABOUT 0.8 TO ABOUT 4 WEIGHT PERCENT OF AN ALKALINE EARTH METAL SULFONATE SELECTED FROM THE GROUP CONSISTING OF CALCIUM AND BARIUM SULFONATES HAVING MOLECULAR WEIGHTS IN THE RANGE OF FROM ABOUT 500 TO 1000, FROM ABOUT 1.8 TO ABOUT 5 WEIGHT PERCENT OF AN ALKALINE EARTH METAL SALT OF AN ALKYL PHENOL SULFIDE SELECTED FROM THE GROUP CONSISTING OF BARIUM SALTS AND MIXED CALCIUM-BARIUM SALTS OF NONYL PHENOL SULFIDE, AND FROM ABOUT 0.2 TO ABOUT 1.0 WEIGHT PERCENT, BASED ON THE TOTAL WEIGHT OF SAID COMPOSITION, OF PHENYL-A-NAPHTHYLAMINE. 